New Protocol for Species Mix Testing in Retail Mulch Sample

Abstract

Many millions of bags of mulch are sold at retail in the United States each year. Most mulch products claim to be of a certain species, with cypress being perhaps the most widely marketed. Unfortunately, it is practically impossible for the average consumer to know with certainty whether a product is indeed the species listed on the packaging. Claims of misleading behavior by some producers raise the question of whether species mix should be more closely monitored. Regulators charged with ensuring fair competition and consumer welfare, however, do not have an accurate means to determine species content. It would be difficult, if not impossible, to determine the species mix for 100% of the wood particles in a package of mulch because of the inability to identify species of the smallest particles, and the impracticality of 100% sampling in the intended use. We propose and develop a new method to allow analysts to estimate the percentage of a given species in samples of mulch, with a focus on cypress. This case study illustrates our methods and highlights the challenges in accurately determining species mix in the type of wood product. We purchased and tested 10 bags of cypress mulch obtained from six different states. Results indicate that one producer was filling some bags with only 50% cypress and others with no cypress. Consumers may therefore suffer as they receive a lower valued species, whereas honest competitors are also harmed. The wood science community could help regulators and consumers by developing a method by which small particles of wood could be positively identified as to species. Improved methods for species identification are relevant for a wide variety of purposes ranging from identifying consumer products to upholding the U.S. Lacey Act.